1. Field of the Invention
The present invention relates to a battery-driven hydraulic excavator driven by electric power from a battery mounted
2. Description of the Related Art
A battery-driven hydraulic excavator driven by electric power from a battery mounted has been known as disclosed in Japanese Utility Model Laid-Open No. Hei 4-53846 Publication. In this hydraulic excavator, power from the battery drives an electric motor, which in turn drives a hydraulic pump. The hydraulic pump drives a working attachment comprising a boom, an arm and a bucket. The hydraulic pump drives the hydraulic motor so that the hydraulic excavator moves forward or backward.
The battery-driven hydraulic excavator is less in noise and exhaust gas as compared with hydraulic excavators of an internal combustion engine type using as a driving source the internal combustion engine such as a gasoline engine, a Diesel engine. Therefore, the battery-driven hydraulic excavator is suitable for operation in a city area where buildings are thickly settled.
In the conventional battery-driven hydraulic excavators, even if one working attachment stops during operation, other working attachments are often operated. Therefore, the hydraulic pump is continuously driven during a period from the start of operation to the termination of operation. Accordingly, when the hydraulic pump is once driven, even if all the working attachment are stopped for reasons of operation during the operation, the hydraulic pump continues to be driven. Moreover, the discharge amount of the hydraulic pump is normally set constant. Also in the case where only a part of the working attachment is operated and in the case where the operation is discontinued, the hydraulic pump is in operation, thus posing a problem in that power of the battery is consumed wastefully to shorten the life of the battery.
In order to overcome such a problem as noted above, it is contemplated that in the state in which all the operating levers are set to a neutral position, a power switch is turned off. However, in order to achieve this, it is necessary to provide a sensor for detecting a neutral position of the operating levers, thus posing a problem in that the cost increases.